Function schedule 

pub fn schedule(delay: Duration, job: impl FnOnce() + Send + 'static) -> TimerId

Run job after delay on the process’s one timer thread, which starts with the first timer. Parts use it for limits and backoff instead of parking a thread per wait. Jobs run one at a time, so a job should hand longer work elsewhere. The browser has no threads: there a timer never fires, and web code keeps its own clock.